The present invention relates to a method for mass production of chitosan by cultivating microorganisms, in particular, those belonging to the family Mucoraceae.
Recently, chitosan has attracted special interest as a biomass which is second to cellulose in importance. Chitosan is expected to be used in various fields, for instance, highmolecular flocculants for waste water and porous beads for immobilizing enzymes and microorganisms and so on. Chitosan is present extensively in the natural world and, therefore, can be prepared through extraction from natural products and purification of the extract. Industrially, chitosan has been prepared by subjecting shells of crustaceans such as shrimps and/or crabs to decalcification and deproteination to isolate chitin and then deacetylating the resulting chitin with a hot concentrated alkali solution.
However, this method requires the use of natural resources such as shrimps and/or crabs whose amount acceptable greatly varies depending on years and seasons and it is likewise apprehended that the natural resources are exhausted. Furthermore, the quality of the resources varies depending on the harvest-time. For this reason, it is difficult to stably supply the ingredients having fixed quality. If the ingredients are stored over a long time period to eliminate such disadvantage, they rot and give out a bad smell during storage, and it makes molecular weight decrease. Furthermore, the waste water discharged during the processes such as deacetylation of chitin is alkaline which has a high level of the biological oxygen demand (BOD) and becomes a cause of environmental pollution.